Multilayered polymer films and process for the preparation thereof

ABSTRACT

The present invention concerns a multilayered polymer film structure, which comprises at least one first layer ( 1 ) containing a thermoplastic polymer and at least one second layer ( 2 ), arranged adjacent to said first layer, containing a liquid crystalline polymer. According to the invention, the second layer ( 2 ) consists essentially of a compounded polymer blend formed by the liquid crystalline polymer and a thermoplastic polymer, the liquid crystalline polymer of the second layer forms a continuous phase, and the first and the second layers ( 1, 2 ) contain the same thermoplastic polymer. The oxygen transmission rate of the second layer is less than about 150 cm 3 /(m 2 ·d·bar), determined according to the standard ASTM D 3985-81, and the water vapour transmission rate of the integral film structure is less than 10 g/(m 2 ·24·h) at RH 80% 23° C., determined according to ASTM F 1249-90. The present structure can be used as a barrier layer in packages.

FIELD OF THE INVENTION

The present invention relates to multilayered polymer film structuresfor use as a barrier layer in packages. Such film structures comprise atleast one first polymer layer having low permeability to moisture and,attached to the first layer, a second polymer layer having lowpermeability to gases, said first film comprising a isotropic polymerand said second film containing a liquid crystalline polymer.

The invention also concerns a process for preparing multilayered polymerfilms based on combinations of isotropic polymer layers and liquidcrystalline polymer layers. Furthermore, the invention relates tolaminates, comprising a substrate and at least one multilayered polymerstructure coated on the surface of said substrate, wherein the polymerlayer acts as a barrier to the transport of gases and moisture throughthe laminate.

BACKGROUND OF THE INVENTION

In food container laminates, aluminum foils have traditionally been usedas sealing layers to protect the foodstuff from deterioration caused bycontact with oxygen and moisture. Nowadays, the aluminum foils are to anincreasing extent being replaced by various polymer films, which havegood barrier properties, but which are more easily degradable in naturethan aluminum. Since no single polymer can provide the same resistanceto gas and water penetration as aluminum, the polymer-based laminatestypically comprise multilayered polymer structures. Often, thesestructures incorporate thermoplastic polymers, such as polyolefins,which are heat sealable and thus make it possible to manufacturecontinuous structures. The polyolefins themselves are known to haveexcellent moisture and water vapor resistance, but they suffer from poorgas barrier properties. Therefore, the multilayered polymer structuresusually include a specific gas barrier material, such as ethylene/vinylalcohol (EVOH), a conventional polyethylene-EVOH-based multi-layerproduct having the following structure: PE/adhesivepolymer/EVOH/adhesive polymer/PE).

It is known that thermotropic liquid crystalline polymers (LCP), haveexcellent barrier properties. However, the processing of them isdifficult due to anisotropic behavior. Because the price of the liquidcrystalline polymers is also rather high, LCP's have not been used asbarrier materials in practical applications.

However, some LCP-based barrier structures are described in the priorart. Thus, EP Patent Application No. 0 503 063 discloses a compositefilm comprising a liquid-crystal polymer layer containing a thermotropicliquid crystal polymer and a thermoplastic polymer layer laminated on atleast one surface of the liquid crystal polymer layer. The polymer layeris fixed on the liquid crystalline polymer through an adhesive layer.The use of such a layer can be avoided by functionalizing thethermoplastic in order to ensure proper attachment to the LCP film.

Similar structures are also described in JP Published PatentApplications Nos. 2 220 821, 2 253 949-2 253 951, and 2 261 456.

U.S. Pat. No. 5,084,352 describes a multilayered barrier film product,which includes a first polymer having low permeability to moisture and aheterogeneous polymer blend film containing a gas barrier polymer. Theheterogeneous film comprises a barrier polymer, such as EVOH, and asecond polymer, distributed within the barrier polymer. The secondpolymer consists of a polyolefin which is functionalized, so as to allowthe heterogeneous polymer film to adhere to the first polymer filmhaving low permeability to moisture. As an example of alternativebarrier polymers, U.S. Pat. No. 5,084,352 also mentions thermotropicliquid crystal polymers. These polymers are, however, not suggested foruse in packaging applications, nor are there any examples given on theactual use of a LC polymer in the described multilayered film product.

The main problem associated with the known barrier structures based onliquid crystalline polymers as a barrier to oxygen penetration residesin the high price of the LC polymer and the difficult processing of theLCP layer. Since only homogeneous LC layers have so far been used, theamount of the liquid crystalline polymer in relation to the othercomponents of the polymer structure becomes rather high, which increasesthe total costs of the barrier structure. Furthermore, homogeneous LCPlayers are brittle and difficult to process with traditional laminationtechniques.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to eliminate theabove problems and to provide a multilayered polymer structureessentially comprising at least a first layer comprising a thermoplasticpolymer and a second layer, attached to the first layer, comprising aliquid crystalline polymer blended with the polymer forming the firstlayer.

It is another object of the present invention to provide a process forpreparing multilayered LCP-containing barrier structures. A third objectof the present invention is to provide laminates containing multilayeredLCP/thermoplastic-film structures.

The present invention is based on the finding that the barrierproperties of anisotropic liquid crystalline polymers are not to anysignificant degree impaired by blending them with a thermotropic polymerprovided that the liquid crystalline polymer forms a continuous layer.Therefore, it is required that the second layer contain about 60 to 99%by volume of an LCP, 40 to 1% by volume of a thermotropic (isotropic)polymer, and 0 to 10% by volume of a compatibilizer. In a layercomprising a blend of at least one anisotropic rigid-rod liquidcrystalline polymer and at least one flexible isotropic polymer, theformer acts as a barrier material against gas penetration because of therigid linear molecules, the packing density of which is high in solidstate. The latter provides resistance to the penetration of water vapor.The isotropic polymer preferably comprises a thermoplastic polymer whichenhances attachment to an adjacent thermoplastic layer. The isotropicpolymer can be functionalized in order to improve attachment.

The oxygen transmission rate of the second layer is typically less thanabout 150 cm³/(m²d bar), determined according to the standard ASTM D3985-81, and the water vapour transmission rate of the integral filmstructure is less than 10 g/(m² 24 h) at RH 80% 23° C., determinedaccording to ASTM F 1249-90.

The prerequisite for proper formation of a continuous liquid crystallinephase is that the blend is melt processed at laminar flow conditions soas to obtain a homogeneous structure. Therefore, the process ofpreparing the above defined monolayer polymer materials comprises thesteps of providing at least one first polymer comprising a isotropicpolymer and processing the first polymer into a film, providing apolymer blend containing about 60 to 99 parts by volume of ananisotropic liquid polymer, 1 to 40 parts by volume of an isotropicthermoplastic polymer, and 0 to 10 parts by volume of a compatibilizerwhich improves the interaction between the anisotropic and the isotropicpolymers of the blend, melt processing the polymer blend at a ratio ofthe viscosity of the anisotropic polymer to the viscosity of theisotropic polymer [λ=η_(anisotropic polymer)/η_(isotropic polymer)]which is in the range of about 0.5 to 5 in order to produce a polymercompound, and processing the polymer compound into a polymer film, andattaching the two films together to form a multilayered structure.Depending on the specific film forming techniques used, the formation ofthe polymer films and the formation of the multilayered structure may becarried out simultaneously or sequentially, preferably the coextrusiontechnique is employed.

The laminate suited for use, for instance, in food containers iscomprised of a substrate, and at least one polymer layer coated on asurface of said substrate to act as a barrier to transport of oxygen andwater vapour through the laminate. The polymer layer is comprised of amultilayered polymer structure having at least one first layercontaining a thermoplastic polymer, and at least one second layerarranged adjacent to said first layer and containing a liquidcrystalline polymer. The second layer consists essentially of acompounded polymer blend formed by the liquid crystalline polymer and athermoplastic polymer. The liquid crystalline polymer of the secondlayer forms a continuous phase and the first and second layers containthe same thermoplastic polymer. The second layer has an oxygentransmission rate of less than 150 cm³/(m²·d·bar), determined accordingto ASTM D 3985-81, and the integral film structure has a water vaportransmission rate of less than 10 g/(m²·24·h) at RH 80% 23° C.,determined according to ASTM F 1249-90.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described below in greater detail withreference to the accompanying drawings, of which

FIG. 1 depicts in a schematic section view the structure of a multilayerfilm according to the invention,

FIG. 2 shows an enlarged sectional view of the second layer of themultilayer film,

FIG. 3 depicts a SEM micrograph of a fractional surface of themultilayered film structure,

FIG. 4a shows a discontinuous LCP phase comprising elongated spheres,

FIG. 4b a co-continuous phase beyond an inversion point, and

FIG. 4c a discontinuous, fine dispersed LDPE phase,

FIGS. 5a and 5 b depict the effect of phase inversion on the filmmorphology using other LCP and PO component than in the situation ofFIG. 4.

FIG. 6 shows the oxygen permeability as a function of the weightfraction of the LCP (in wt-%) for different polymer film samples, and

FIGS. 7a and 7 b depict the fracture surface of the barrier layer of afilm structure based on a different LCP than the one shown in FIGS. 4and 5.

DETAILED DESCRIPTION OF THE INVENTION Definitions

Within the scope of the present invention the term “film” encompassesthin structures having at least substantially flat and smooth surfaces.Thus, in the following, the term “film” is used synonymously with“sheet”.

The term “isotropic polymer” designates any thermoplastic polymer whichdoes not decompose below its degradation point and which therefore canbe melt processed in the area between the melt or glass transition anddegradation temperatures.

The term “anisotropic liquid crystalline polymer (LCP)” is used forpolymers which in liquid state, in particular as an ordered melt(=thermotropic LCP's), lie between the boundaries of solid crystals andisotropic liquids.

Physical mixtures of two or more (neat) polymers, if desired mixed withsuitable additives and adjuvants, are called “blends”, whereas the term“compounds” designates polymer blends typically also containingadditives and adjuvants, which have been processed into a homogeneousmixture, which can be used for the manufacture of the polymer product,for instance a film or a sheet. Polymer blends do not form single-phasesystems in material processing and application conditions and theirproperties depend on the dispersion of the components and are usuallylinked to the arithmetic average of the values of the components.

For the purpose of this description the term “compatibilizer” means asubstance which promotes the compatibility of the isotropic andanisotropic components of the compounds.

“Reactive compatibilizer containing functional groups” denotes a polymerwhich is capable of reacting with at least one of the components of theblend. In practice it is difficult to determine the exact nature of theinteraction between the compatibilizer and the other components of theblend, and to ascertain whether a chemical reaction has taken place ornot. Therefore, within the scope of the present application, allpolymers which contain functional groups capable of reacting with thefunctional groups of the matrix polymer and/or the liquid crystallinepolymer, are considered to be reactive compatibilizers.

In the following description and in the examples, the composition of thepresent compounds of isotropic and anisotropic polymers are indicated inweight or volume percent. The volume fraction of the LCP can becalculated by using the following formula:

V_(f)=[W_(f)/δ_(f)/W_(f)/δ_(f)+W_(m)/δ_(m))]×100%

wherein

δ_(f)=density of reinforcement

δ_(m)=density of matrix

W_(f)=weight fraction of reinforcement

W_(m)=weight fraction of matrix

The Polymer Film Components

As mentioned above, the polymer films of the second layer are comprisedof isotropic and anisotropic polymers which together provide acompounded blend, the anisotropic polymer forming the continuous phaseof the blend. Although the isotropic polymer to some extent is dispersedthroughout the blend, it mainly gathers on the surface of it.Optionally, the polymer films further contain compatibilizers andadditives and adjuvants.

The liquid crystalline polymer of the monolayer may, for instance,comprise an aromatic main chain anisotropic polymer, preferably ananisotropic polyester, poly(ester amide), poly(ester ether), poly(estercarbonate) or poly(ester imide). It can also comprise a copolymer of apolyester, such as a copolymer of poly(ethylene terephthalate) andhydroxy benzoic acid or a copolymer of hydroxynaphthoic acid andhydroxybenzoic acid.

Generally, the liquid crystalline polymer, which is used in the presentinvention, can be defined as a polymer which is formed when thecomponents of the following general formulas (or at least two of them)are reacted with each other: a dicarboxylic acid of formula I

HOOC—R₁—COOH  (I)

a diol of formula II

HO—R₂—OH  (II)

a hydroxycarboxylic acid of formula III

 HO—R₃—COOH  (III)

wherein

R₁, R₂, and R₃ each independently represents

a bivalent aromatic hydrocarbon group,

a group of formula R₄—X—R₅, wherein R₄ and R₅ represent a bivalenthydrocarbon group and X is an oxygen or a sulphur atom, a sulphonyl,carbonyl, alkylene, or ester group or X is a single bond,

a xylylene group or

a bivalent aliphatic hydrocarbon group.

The liquid crystalline polymer can also comprise a homopolymer of ahydroxycarboxylic acid of formula IV

HO—R₃—COOH  (IV)

Typically, the aromatic dicarboxylic acids of formula I are selectedfrom the group comprising terephthalic acid, isophthalic acid,4,4′diphenyl-dicarboxylic acid, diphenyl ether-4,4′-dicarboxylic acid,diphenylethane-3,3′-dicarboxylic acid, diphenylethane-4,4′-dicarboxylicacid, diphenyl ether-3,3′-dicarboxylic acid, 4,4′-triphenyl-dicarboxylicacid, 2,6-naphthalenedicarboxylic acid,diphenoxyethane-4,4′-dicarboxylic acid,diphenoxybutane-4,4′-dicarboxylic acid,diphenoxyethane-3,3′-dicarboxylic acid, and naphthalene-1,6-dicarboxylicacid.

Said aromatic dicarboxylic acids may be alkyl-, alkoxy-, orhalogen-substituted. The substituted derivatives can be selected fromthe group comprising chloroterephthalic acid, dichloroterephthalic acid,bromoterephthalic acid, methylterephthalic acid, dimethylterephthalicacid, ethylterephthalic acid, methoxyterephthalic acid, andethoxyterephthalic acid.

The alicyclic dicarboxylic acids of formula I can be selected from thegroup comprising trans-1,4-cyclohexanedicarboxylic acid,cis-1,4-cyclo-hexanedicarboxylic acid, and 1,3-cyclohexanedicarboxylicacid.

The alicyclic dicarboxylic acids may also be substituted by one or morealkyl-, alkoxy-, or halogen-substituent(s). The substituted dicarboxylicacid derivatives can be selected from the group comprisingtrans-1,4-(1-methyl)-cyclohexane-dicarboxylic acid andtrans-1,4-(1-chloro)cyclohexane-dicarboxylic acid.

The aromatic diols of formula II can be selected from the groupcomprising hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl,4-4′-dihydroxytriphenyl, 1,6-naphthalenediol, 2,6-naphalene-diol,4,4′-dihydroxydiphenyl ether, 3,3′-dihydroxydiphenyl,1,1-bis(4-hydroxyphenyl)-methane, bis(4-hydroxyphenoxy)-ethane,2,2-bis(4-hydroxyphenyl)propane, and 3,3′-dihydroxy-diphenyl ether.These diols may be substituted by one or more alkyl-, alkoxy-, orhalogen substituent(s), which derivatives are exemplified by thefollowing list: chlorohydroquinone, methylhydroquinone,1-butylhydroquinone, phenylhydroquinone, methoxy-hydroquinone,phenoxyhydroquinone, 4-chlororesorcinol, and methylresorcinol.

Typical examples of alicyclic diols of formula II include trans- andcis-1,4-cyclohexanediols, trans-1,4-cyclohexane-dimethanol,trans-1,3-cyclohexanediol, cis-1,2-cyclohexanediol, andtrans-1,3-cyclohexanedimethanol. Instead of these compounds thecorresponding alkyl-, alkoxy-, or halogen-substituted derivatives can beused, as well.

The aliphatic diols of formula II can be straight-chained or branchedand selected from the group comprising ethylene glycol, 1,3-propanediol,1,4-butanediol, and neopentyl glycol.

The aromatic hydroxycarboxylic acids of formula III are selected fromthe group comprising 4-hydroxybenzoic acid, 3-hydroxybenzoic acid,6-hydroxy-2-naphthoic acid, and 6-hydroxy-1-naphthoic acid. Thesecompounds can be alkyl-, alkoxy-, or halogen-substituted. Thesubstituted aromatic hydroxycarboxylic acid derivatives are preferablyselected from the group comprising 3-methyl-4-hydroxybenzoic acid,3,5-dimethyl-4-hydroxybenzoic acid, 2,6-dimethyl--4-hydroxybenzoic acid,3-methoxy-4-hydroxy-benzoic acid, 3,5-dimethoxy-4-hydroxybenzoic acid,6-hydroxy-5-methyl-2-naphthoic acid, 6-hydroxy-5-methoxy-2-naphthoicacid, 3-chloro-4-hydroxybenzoic acid, 2,3-dichloro-4-hydroxybenzoicacid, 3,5-dichloro-hydroxybenzoic acid, 2,5-dichloro-4-hydroxybenzoicacid, 3-bromo-4-hydroxybenzoic acid, 6-hydroxy-5-chloro-2-naphthoicacid, 6-hydroxy-7-chloro-2-naphthoic acid, and6-hydroxy-5,7-dichloro-2-naphthoic acid.

In addition to the above mentioned polyesters, the LCP's used in themultilayered structures according to the invention can comprise thecorresponding polyester amides. It is also possible to use polymershaving a main chain containing conjugated double bonds, the monomerunits of said main chain being linked to unsubstituted or substitutedside chains which, together with the main chain render the polymerliquid-crystal properties. Examples of such polymers are polytiophene,polyaniline, polyacetylene, polypyrrole and polyparaphenylenesubstituted with alkyl chains containing at least 8 carbon atoms.

The following list exemplifies some preferred embodiments of the liquidcrystalline polymers:

copolyesters of terephthalic acid, alkylhydroquinone, p-hydroxybenzoicacid and poly(alkylene terephthalate), the alkylene substituentpreferably comprising ethylene or butylene and the alkyl substituent ofthe hydroquinone preferably comprising a lower alkyl group such aspropyl or (tertiary) butyl,

copolyesters of p-hydroxybenzoic acid and poly(alkylene terephthalate),the alkylene group preferably being ethylene or butylene,

copolyesters of terephthalic acid, alkylhydroquinone, p-hydroxybenzoicacid and hydroxyalkylphenyl-alkanoic acids, the alkyl-substituent of thehydroquinone preferably comprising a lower alkyl group such as propyl or(tertiary) butyl, the alkanoic acid preferably containing 3 to 8 carbonatoms, propanoic acid being particularly preferred, and

blockcopolyesters of trimellithic imide-terminated poly(THF) orpolysilicone, containing the imide group in para- or meta-position i.e.N-(4-carboxy-phenyl)-trimellit imide or N-(3′-acetoxy-phenyl)-trimellitimide, with acetoxybenzoic acid and at least one repeating unit selectedfrom the group comprising diacetoxy diphenyl, hydroquinone diacetate,terephthalic acid, a trimer designated HBA—HQ—HBA (the synthesis ofwhich is described in Europ. Polym. J. 20, 3, 225-235 (1984), andpoly(ethylene terephthalate) (PET).

According to the invention, it is particularly preferred to use fullyaromatic liquid crystalline polymers containing naphthalenic units.These kinds of LCP's are particularly well suited for use as barriercomponents in blends with thermotropic polymers.

The molecular weight of the liquid crystal polymer used in the presentinvention depends on the character of the repeating units of the LCP.Usually, the molecular weight is in the range of about 1,000 to 300,000.If fully aromatic polyesters are used as LCP's, their molecular weightis typically in the range of about 2,000 to 200,000, preferably about10,000 to 50,000.

More general details on liquid crystalline polymers and their propertiesand applications are given in an article titled “Liquid Crystal Polymersand Their Applications” by Chung et al. in Handbook of Polymer Scienceand Technology, Vol. 2 (1989) 625-675.

The isotropic polymer of the multilayered structure can comprise anysuitable polymer material which has the desired properties regardingresistance to penetration of water vapor as well as regarding strengthand processability.

As examples of the isotropic polymers, the following may be mentioned:polyolefins such as polyethylene, polypropylene, polybutylene,polyisobutylene, poly(4-methyl-1-pentylene), including copolymers ofethylene and propylene (EPM, EPDM) and chlorinated (PVC) andchlorosulphonated polyethylenes. The isotropic polymer may also becomprised of the corresponding polyalkanes, which contain styrene (PS),acryl, vinyl and fluoroethylene groups, and different polyesters, suchas poly(ethylene terephthalate), poly(butylene terephthalate) andpolycarbonate, polyamides and polyethers (e.g. poly(phenylene ether).Particularly preferred polymers are the polyolefins, such as LDPE,VLDPE, MDPE, HDPE and PP and random copolymers of propylene andethylene.

The molecular weights of the preferred isotropic thermoplastic polymersare usually in a range from about 5,000 to 50,000, preferably about10,000 to 30,000. The flexural modulus (0.5-0.25%) of the matrix polymeris preferably about 100-10.000 MPa, in particular about 500-5000 MPa.

When compatibilizers are used in the compounds according to theinvention, they typically comprise functionalized (reactive) polymers,in particular polyolefins, block- or grafted copolymers of polyolefinsand polyesters, or non-polymeric surfactants. Of the functional groupsof the reactive compatibilizers, the following should be mentioned:carboxy, anhydride, epoxy, oxazolino, hydroxy, amine, carbonyl,iso-cyanate, acylacetam and carbodiimide groups, the eight first beingparticularly preferred. The compatibilizers may also containcombinations of these groups. The polymer residues of the compatibilizercan comprise co- and terpolymers, grafted polyolefins, graftedpolystyrene and thermoplastic elastomers. The polar groups ofpolyolefinic copolymers are generally acrylic esters or functionalacrylic acid groups and maleic anhydride groups. The polar groups of theterpolymers can be maleic anhydride groups, hydroxyl groups and epoxygroups, of which the first-mentioned are particularly preferred. Thestyrene block copolymers can consist of polystyrene segments andflexible elastomer segments. Typical styrene block copolymers are SBS(styrene/butadiene/styrene-copolymer), SIS(styrene/isoprene/styrene-copolymer) and SEBS (styrene/ethylenebutylene/styrene-copolymer).

Particularly preferred are block- or grafted copolymers comprisingpolyolefin groups and groups of polar polymers, the groups beingincorporated into the main chain or grafted to either polymer.

Of the non-polymeric surfactant compatibilizers, the following should bementioned: neoalkoxy titanate and neoalkoxy zirconate, alkyl silane,alkyl sulfonic acid and alkyl carboxylic acid.

Of the polymer blend additives, fillers, pigments and various substanceswhich promote the processing of the blend can be mentioned.

Plastic additives known per se can be added to the polymer blendaccording to the invention. These additives comprise, for instance,stabilizers, colouring agents, lubricants, antistatic agents, fillers(e.g. talc and mica) and fire retardants. If desired, these substancescan be premixed with, e.g., the isotropic polymer before forming thepolymer blend. The amounts of polymer additives are typically about 0.01to 5%, preferably about 0.1 to 2% of the weight of the polymer blend.

Of the isotropic/anisotropic compounds according to the invention, thefollowing are particularly preferred:

Compounds containing 60 to 99 parts by volume of a fully aromaticcopolyester or polyesteramide liquid crystalline polymer, and 1 to 40parts by volume of isotropic polyolefins, such as polyethylene orpolypropylene. For good attachment to adjacent layers of thermotropicpolymer it is preferred to include any compatibilizer in the compounds.The addition of a compatibilizer will also improve the impact strengthof the blend and dispersion of the isotropic component. Typically, anamount of about 0.1 to 5, in particular 1 to 4, parts by volume of acompatibilizer can be included.

Structure of the Multilayered Film

The structure of a section of the multilayered film is depicted in FIG.1. FIG. 2 shows in more detail the structure of a section of the barrierlayer of the multilayered film.

As shown in FIG. 1, a three-layered film structure comprises two layersof a isotropic polymer 1, 3 attached on each side of a barrier layer 2.The barrier layer 2 contains a homogeneous, continuous LCP phase 4 andlaminar areas 5 of an isotropic polymer located primarily in the surfaceregions of the LCP phase.

It should be noticed that FIG. 2 represents a simplified hypotheticalcase, wherein the isotropic polymer is largely gathered in the clearlydefined lamellar layer(s) close to the surface. In practice, theisotropic polymer is at least to some extent dispersed throughout thematrix polymer and the “layers” simply represent high concentrationregions.

FIG. 3 depicts a typical fraction surface SEM micrograph relating to amultilayer film structure. The dispersion of the isotropic polymer inthe LCP matrix is clearly seen as is the continuous LCP phase.

This invention shows that the LCP content of the blend layer has to beso high that the LCP forms a continuous phase beyond an inversion point.When the LCP content is too low, as is the case in a compound composedof 60 wt-% of a LCP (Vectra B950 from Hoechst Celanese), 37 wt-% of LDPE(NCPE 1515 from Neste Oy) and 3 wt-% of a compatibilizer (Lotader 8660from Norsolor), the LCP phase is discontinuous and comprises elongatedspheres (FIG. 4a). An increase from 60 to 70 wt-% in the LCP contentresults in phase inversion and the isotropic and anisotropic componentsbecome sheet-like (forming a co-continuous phase), as shown in FIG. 4b.Further increase of the LCP content from 70 to 80 wt-% will break downthe isotropic component (LDPE) into a fine-dispersed phase (FIG. 4c).These morphological changes directly reflect the oxygen and waterpermeability (FIG. 6). The same trend can be seen in FIGS. 5a and 5 bwhen comparing two compounds, one of which is composed ofLCP/Novaccurate E322 from Mitsubishi Kasei (50 wt-%), LDPE NCPE 4524from Neste Oy (57 wt-%) and compatibilizer/Lotader 8660 from Norsolor (3wt-%) and the other of LCP/Novaccurate E322 from Mitsubishi Kasei (70wt-%), LDPE NCPE 7513 from Neste Oy (27 wt-%) and compatibilizer/Lotader8660 from Norsolor (3 wt-%).

Thus, in summary, the LCP content is crucial to the oxygen and watervapor permeability of the structures according to the invention. As theexamples show, with LCP weight fractions of about 80 percent by weight(corresponding to about a 70 percent volume fraction), structures wereobtained having an oxygen barrier on the same level as the best knownbarrier polymer (such as EVAL). Experimental data show a clearimprovement of the oxygen barrier of the polymer structures at LCPcontents in excess of the inversion point of the blends. The lower limitof the LCP of the monolayer structures according to the invention istherefore set at about 50 vol-%.

The thickness of the barrier structure depends on the processingconditions and the relative amounts of the various components of thepolymer compounds. It has been found that the brittleness problemsrelated to homogeneous LCP films can be avoided almost entirely bymanufacturing thin barrier film layers having an average thickness ofless than 50 μm. A range of about 0.1 to about 10 μm is preferred. Atsuch thicknesses (in particular the thicknesses of the preferred range),the LCP blend layer is homogeneous, smooth and glossy and it has theflexibility needed for further processing as a part of a barrierlaminate.

Polymer Processing

Generally, the isotropic and anisotropic polymers are first mixed inorder to form a blend which optionally contains additives and adjuvants.Then, the liquid crystalline polymers are compounded with thethermoplastics by melt processing. The applicable mixing methods includebatch or continuous processes. Preferably single- or twin-screwextruders are used for compounding the liquid crystalline polymer withthe thermoplastic.

The compounds according to the invention are processed according tomethods known per se in polymer technology to manufacture the finalproducts.

The basic principle governing the compounding and processing of theblend component into the final products is the morphology control of theisotropic/anisotropic blend which can be achieved by differentprocessing techniques. As mentioned above, the best barriers of thefinal applications are obtained when the anisotropic LCP forms acontinuous phase and the isotropic polymer is gathered at the surfaceareas thereof. The morphology of the LCP/isotropic polymer layer ispreferably laminar. Such morphology can be generated, e.g. byco-extrusion, blow molding, film extrusion, and co-injection molding.Because the liquid crystalline polymer blends are “in situ” compounds apreferred embodiment of the invention comprises processing the blends byextrusion using sheet dies or rotating dies or stenter frame or filmblowing, i.e. biaxial processing methods. For multilayer film andsheet-like structures the best processing alternatives are comprised ofthe co-extrusion and co-injection molding techniques.

It is known that elongational flow is more effective in inducingorientation of LCP's than shear. In fact, the orientation buildup ofLCP's is independent of shear rate, the more pseudoplastic the flowingbehavior, the more orientated the polymer. Also longer dies give rise tobetter orientation. Thus, the processing technique for preparing thestructures of the invention should preferably provide biaxialorientation of the compounds based on elongational deformation indraw-down or on shear, for example during cooling. Extrusion using longdies and/or processing times is therefore advantageous.

The permeabilities of, in particular, uncompatibilized PO/LCP-blends canbe controlled with the aid of the processing parameters, especially inmultilayer film extrusion. Incompatibility of blend components favoursdomain formation of the minor component. When the amount of the LCPcomponent is larger than that of the isotropic polymer, it has beenfound that in the multilayer film extrusion the viscosity ratio, λ, ofthe LCP and the isotropic polymer [λ=η_(LCP)/η_(MATRIX POLYMER)] shouldbe as close to 1 as possible. Preferred are viscosity ratios in therange from about 0.5 to 5, in particular in the range from about 0.8 to1.2. This leads to laminar flow of the two components and to theformation of a continuous sheet-like LCP phase.

FIG. 6 shows the oxygen permeability of isotropic polymer/anisotropicpolymer compounds as a function of the LCP content.

For the purpose of comparing compounds prepared with different LCP's,four polymer compounds were prepared containing 40, 60, 70 and 80 wt-%of a polyesteramide LCP (Vectra B950, supplied by Hoechst-Celanese), theisotropic polymer of the compounds being a LDPE (NCPE 1515, supplied byNeste Oy). Another series of LCP/LDPE compounds having the sameLCP-contents were prepared using a polyester LCP (Novaccurate E322supplied by Misubishi Kasei), and finally a third series of LCP/LDPEcompounds containing 60, 80 and 100 wt-% LCP was prepared using apolyester LCP (Rodrun supplied by Unitika).

The oxygen permeabilities of a number of known barrier materials areshown in FIG. 6.

It is evident from the figure that when the LCP content of a LCP/PEcompound increases over 50%, a phase inversion takes place. After theinversion point, the LCP forms the continuous phase and the oxygenpermeability radically decreases in the films according to theinvention. The permeability of these LCP/PE compound films with 60 to 70vol-% LCP is very close to the best known barrier polymer (EVOH). Thebest blends have barrier properties which are on the same level as lowethylene content EVOH even in dry conditions. Moisture has no effect onthe barrier properties of LCP blends and the water barrier propertiesare also good. It will also be apparent from the figure that the barrierproperties of LCP blends are not significantly lower than those ofhomogeneous LCP polymers.

Many isotropic polymers, in particular the polyolefins, have goodresistance to penetration of water vapor. The structures according tothe invention will provide good to excellent resistance to oxygenpenetration while still maintaining most of the low water vaporpermeability properties of the polyolefins.

Laminate Applications

The film structures according to the invention can be used for thepreparation of laminates. In addition to the film structures, thelaminates according to a preferred embodiment of the invention compriseat least one layer consisting of a lignocellulosic material made up of,for instance, cellulose fibers. However, it is also possible to preparelaminates comprising films of other polymeric materials.

The cellulose fiber layers in the laminate can be comprised of paperwebs, paperboard webs or similar cellulose based products. The cellulosecontained in the layers can stem from chemical or mechanical pulp whichfurther can be bleached or unbleached pulp.

The surface area weight of the material used for the cellulose fiberlayer is typically approx. 10 to 500 g/m². Typically, paperboard with asurface area weight of approx. 100 to 250 g/m² is employed.

In addition to the barrier layer and the outer layer attached to it, thecellulose fiber-based laminates can contain other polymer layers aswell. Said layers can be formed from thermoplastic polymers such aspolyolefins, polyesters or similar polymers. Different types ofcopolymers are also suitable for use in the polymer material layers. Asan example of a suitable copolymer, an ethylvinyl acetate copolymer canbe mentioned. The polymer or the cellulose fiber material can bereplaced by regenerated cellulose polymer materials such as cellophane.The surface area weights of the polymer layers in the laminate are inthe range of approx. 1 to 250 g/m², preferably approx. 5 to 100 g/m².

The laminates according to the invention can be produced by laminating afilm of the multillayered structure on a cellulosic fiber or polymericlayer by methods known per se. Thus, the method can be implemented byusing extrusion coating, the polymer structure being produced byextrusion into a multilayered sheet which is adhered to the surface of acellulose fibre web. A second polymeric layer, which is applied oneither side of the polymer/cellulosic layer combination, can be adheredat another stage. The method can also be implemented by using extrusionlaminating which operates by feeding said polymer sheet from theextruder between at least two webs and then adhering it to these. One orboth of the webs can be formed by a cellulose fibre web and/or a secondpolymer material. This method is implemented particularly advantageouslyusing the coextrusion technique in which all polymer layers of thelaminate are produced in a single stage in a coextruder.

The laminates according to the invention can be produced into packagingmaterials, bags, wrappers, moisture-proof papers and similar productsexhibiting oxygen and moisture vapor barrier capability. Paperboardgrades for liquid product packages, e.g., milk and juice cartons, arepreferred applications for the laminates described above.

Industrial Applicability

As mentioned above, the structures according to the invention can beused in barrier vessels (e.g. gasoline tanks), barrier containers (e.g.containers for foodstuffs, household chemicals and other chemicals; foodjars, microwave cups), and barrier films (e.g. barrier layer in liquidpackages and bottles). One particularly suitable substrate for themultilayered structures comprises paperboard.

In the following, the invention will be illustrated with the help ofworking examples describing the preparation of multilayered filmstructures.

The oxygen gas and water vapor permeabilities of the LCP-LDPE films weretested according to the following standards:

oxygen gas transmission rate: ASTM D 3985-81 (Reapproved 1988)

water vapor transmission rate: ASTM F 1249-90

The Standard Test Method ASTM D 3985-81 employes a coulometric sensorfor determining oxygen gas transmission rate (O₂GTR) through plasticfilm and sheeting. The sample to be tested is first equilibrated in adry-test environment, the relative humidity of which is less than 1%.Then the specimen is mounted as a sealed semi-barrier between twochambers at ambient atmospheric pressure. One chamber is slowly purgedby a stream of nitrogen and the other chamber contains oxygen. As oxygengas permeates through the film into the nitrogen carrier gas, it istransported to the coulometric detector where it produces an electricalcurrent, the magnitude of which is proportional to the amount of oxygenflowing into the detector per unit time.

The barrier results are based on at least two specimens. The gas andwater vapor transport coefficients for the films having varyingthickness were calculated for a theoretical value of 25 μm.

EXAMPLE 1

A three-layered structure was prepared comprising an intermediatepolymer film layer containing a LCP/thermoplastic polymer blend and twoouter layers consisting of a thermoplastic polymer film, one outer layerbeing attached to each side of the intermediate film.

As thermoplastic material, a LD polyethylene of grade NCPE 1515 waschosen. This polyethylene is supplied by Neste Oy, Finland. The liquidcrystalline polymer (LCP) used was a poly(ester amide) marketed underthe name Vectra B950 (Hoechst Celanese). A random terpolymer ofethylene, butylene acrylate and glycidyl methacrylate (E/BA/GMA)supplied by Norsolor under the trade name Lotader AX 8660 was used as acompatibilizer (COMP) in the LCP-based blend.

The polymer compound for the intermediate layer was produced with atwin-screw extruder at a temperature of 290° C. The compound waspelletized. A three-layer film was then prepared by coextrusion using aconventional plane film apparatus.

The recipe of the LCP-PO compound blend was

LCP 80.0 wt-% LDPE 17.0 wt-% Compatibilizer  3.0 wt-%

The permeability of the film to oxygen and water vapor was assessed bythe above-mentioned standard methods, based on a theoretical filmthickness of 25 μm. The oxygen permeability of the film calculated forthe PO/LCP blend layer was 0.63 ml/(m² 24 h bar) at 23° C. at dryconditions, and the water vapor permeability was 1.4 g/(m² 24 h) at 23°C. and at a relative humidity (RH) of 80%. At damp conditions (RH=86%,T=23° C.), the oxygen permeability was 0.12 ml/(m² 24 h bar).

EXAMPLES 2 to 4

Further three-layered structures were prepared from LDPE and differentliquid polymer blends. The composition of the intermediate layer and thepermeabilities of the film structures are indicated in Table 1. Theliquid crystalline polymer used in these examples comprised acopolyester of p-hydroxybenzoic acid (HBA) and polyethyleneterephthalate(PET) marketed under the name Rodrun LC-3000 (Unitika Ltd.). Thisspecific LCP has a PHB/PET molar ratio of 60/40, the relative viscosityη_(rel) is 1.42 (tetrachloroethane/phenol=1/1, 35° C.), and the glasstransition point is 64° C.

TABLE 1 Compositions and properties of three-layered film structuresOxygen Water vapor Inter- Example Blend permeability permeability facial# composition ml/(m² 24 h bar) g/(m² 24 h) adhesion 2 80 wt-% LCP  294.0 rather 17 wt-% LDPE poor 3 wt-% COMP 3 60 wt-% LCP 100 4.9 fair 40wt-% LDPE 4 60 wt-% LCP 610 3.24 good 37 wt-% LDPE 4 wt-% COMP

The oxygen permeability was measured at 23° C. and dry conditions.

The water vapor permeability was measured at 23° C. and RH 85%

EXAMPLE 5

Two three-layered film structures were prepared as described inExample 1. In one of the films, the LCP-based polymer blend was composedof 70 wt-% LCP (Vectra B950), 27 wt-% PE (NCPE 1515) and 3 wt-%compatibilizer (Lotader 8660), whereas the other blend was composed of40 wt-% LCP (Vectra B950) 57 wt-% PE (NCPE 1515) and 3 wt-%compatibilizer (Lotader 8660). In the latter case, with thepolyesteramide LCP used, the LCP content was not high enough forformation of a continuous phase, which is apparent from the resultsgiven in Table 2, and which can be seen in FIGS. 4a and 4 b.

TABLE 2 Composition and oxygen permeability of three-layered filmstructures Oxygen permeability Sample Blend composition ml/(m² 24 h bar)A 70 wt-% LCP 1.0 27 wt-% LDPE 3 wt-% COMP B 60 wt-% LCP 4600 37 wt-%LDPE 3 wt-% COMP

EXAMPLE 6

Two LDPE/LCP blends were compounded by twin-screw extrusion. One of thecompounds was composed of the commercial thermotropic polyesteramideVectra B950 and the other of the commercial thermotropic polyesterVectra A950. The recipes of blends for the middle barrier layer were thefollowing:

Recipe 1: Vectra B950 80 wt-% NCPE 1515 17 wt-% Lotader 8660  3 wt-%Recipe 2: Vectra A950 80 wt-% NCPE 1515 17 wt-% Lotader 8660  3 wt-%

These compounds were coextruded into the 3-layer films having LCP/NCPE1515 skin layers. The melt temperature was 300° C. in the case of recipe1, whereas the second recipe was extruded at temperatures of 300° C. and280° C.

Only the polyesteramide LCP-based compound was successfully extrudedinto a 3-layer film structure. The thickness of the whole film was 135μm and that of the blend barrier layer 70 μm. The measured oxygen gastransmission rate and water vapor transmission rate was 0.32 cm³(m²·d·bar) and 0.32 g/(m²·d), respectively, for the barrier layer.

Multi-layer extrusion of the polyester LCP-based compound (recipe 2) wasnot successful. By using conventional flat film dies the melt flow ofthis blend was very unstable and turbulent, not laminar, resulting in anunhomogeneous film with holes and thickness variation both in length andwidth direction. The main reason for the difference between thepolyesteramide and the polyester LCP-based blends are dissimilar meltelasticity due to hydrogen bonding. The fracture surface of themonolayer film processed from the recipe 2 indicates that the mophologyof LDPE/LCP barrier layer resembles that shown in FIG. 4 (FIGS. 7a and 7b). FIG. 7a depicts the fracture surface of the recipe 2 melt-processedat 280° C. and there are no distinct differences between lamellar layersthrough the thickness direction, i.e. the lamellae are fused together.When the processing temperature was raised to 300° C., the fracturesurface was transformed into heterogeneous and distinct layers can bediscerned (FIG. 7b). The polyesteramide LCP-based compound (Vectra B950)resulted in more fine fibrillar barrier layer than the polyesterLCP-based one (Vectra A950).

In addition, the morphological changes reflects to melt extrusion duringthe phase inversion stage. The minor isotropic phase has to betransformed into a fine-dispersed phase through a co-continuous phasestage, which is a prerequisite for successful multi-layer extrusion.

What is claimed is:
 1. A multilayered polymer film structure for use asa barrier layer in packages, consisting essentially of: at least onefirst layer containing a polyolefin; at least one second layer arrangedadjacent to said first layer and containing a liquid crystallinepolymer, the second layer consisting essentially of a compounded andcompatibilized polymer blend formed by the liquid crystalline polymer, apolyolefin and a compatibilizer, the liquid crystalline polymer of thesecond layer forming a continuous phase, the second layer having anoxygen transmission rate of less than 150 cm³/(m²·d·bar), determinedaccording to ASTM D 3985-81, and the integral film structure having awater vapour transmission rate of less than 10 g/(m²·24·h) at RH 80% 23°C., determined according to ASTM F 1249-90, the second layer containing60 to 99 parts by volume of the liquid crystalline polymer, 1 to 40parts by volume of the polyolefin, and 0.1 to 5 parts by volume of thecompatibilizer enhancing an interaction between the liquid crystallinepolymer and the polyolefin, contents of the polymers and thecompatibilizer being based upon total volume of the second layer; and atie layer of maleic anhydride modified polyolefin that adheres thesecond layer to the first layer.
 2. A polymer film structure accordingto claim 1, wherein the second layer has a thickness of less than 50 μm.3. A polymer film structure according to claim 1, wherein the liquidcrystalline polymer is comprised of one of an at least partiallyaromatic polyester and a copolymer of an aromatic polyester.
 4. Apolymer film structure according to claim 3, wherein the liquidcrystalline polymer is one of the group consisting of a polyester amide,a polyester imide, polyester ether and polyester carbonate.
 5. A polymerfilm structure according to claim 4, wherein the liquid crystallinepolymer is polyesteramide.
 6. A polymer film structure according toclaim 3, wherein the liquid crystalline polymer is comprised of one ofthe group consisting of an aromatic polyester and a polyester amide, atleast one monomer of which is comprised of a naphthalenic compound.
 7. Apolymer film structure according to claim 6, wherein the second layercontains 60 to 90% by volume of the liquid crystalline polymer, 40 to10% by volume of the polyolefin and up to 10% by volume of thecompatibilizer.
 8. A polymer film structure according to claim 1,wherein the polyolefin comprises a polymer selected from the groupconsisting of LDPE, VLDPE, MDPE, HDPE and PP and random copolymers ofpropylene and ethylene.
 9. A polymer film structure according to claim1, wherein the compatibilizer comprises one of the group consisting of afunctionalized polyolefin, one of a block copolymer and a graftedcopolymer of polyolefin and a polyester, and a non-polymeric surfactant.10. A polymer film structure according to claim 9, wherein thefunctionalized polyolefin comprises a olefinic polymer functionalizedwith one of epoxy, carboxylic acid, anhydride, hydroxyl, amine, carbonyland oxazoline groups and combinations thereof.
 11. A polymer filmstructure according to claim 9, wherein the block copolymer comprisespolyolefin groups and groups of polar polymers, the groups beingincorporated into a main chain.
 12. A polymer film structure accordingto claim 9, wherein the grafted copolymer comprises polyolefin groupsand groups of polar polymers, the groups being grafted to eitherpolymer.
 13. A polymer film structure according to claim 9, wherein thenon-polymeric surfactant comprises alkyl silane, one of neoalkoxytitanate and neoalkoxy zirconate, and one of alkyl sulfonic acid andalkyl carboxylic acid.
 14. A polymer film structure according to claim1, wherein the tie layer is maleic anhydride grafted copolyethylene. 15.A polymer film structure according to claim 1, wherein at least twofirst polymer layers are provided, one on each side of the second layer.16. A polymer film structure according to claim 1, wherein the first andsecond layers have an extruded structure.
 17. A polymer film structureaccording to claim 16, wherein the extruded structure is formed bycoextrusion.
 18. A polymer film structure according to claim 16, whereinthe extruded structure is any one of a blow-molded bottle, container andcan.
 19. A process for preparing a multilayered polymer film, comprisingthe steps of: providing a first polymer consisting of a polyolefin; meltprocessing said first polymer to produce at least one first polymerlayer; providing a polymer blend comprising about 1 to about 40 parts byvolume of a polyolefin, about 99 to 60 parts by volume of an anisotropicliquid crystalline polymer, and 0.1 to 5 parts by volume of acompatibilizer; melt processing said polymer blend at a viscosity ratiobetween the anisotropic polymer and the polyolefin[λ=η_(anisotropic polymer/ηisotropic polymer] in a range of about) 0.5to 5 to produce a polymer compound essentially consisting of a laminarlayer composed of a continuous liquid crystalline polymer base; andprocessing said polymer compound into a second polymer layer, the secondlayer having an oxygen transmission rate of less than about 150cm³/(m²·d·bar), determined according to ASTM D 3985-81, and themultilayered polymer film having a water vapor transmission rate of lessthan 10 g/(m²·d·bar) at RH 80% 23° C., determined according to ASTM F1249-90.
 20. A process according to claim 19, wherein said polymer blendprocessing step includes processing the polymer blend at a viscosityratio of about 0.8 to about 1.2, said ratio resulting in stable laminarflow of the polymer blend.
 21. A process according to claim 19, whereinthe melt processing and film processing include extruding.
 22. Alaminate, comprising: a substrate; and at least one polymer layer coatedon a surface of said substrate to act as a barrier to transport ofoxygen and water vapour through the laminate, the polymer layer beingcomprised of a multilayered polymer structure consisting essentially ofat least one first layer consisting of a polyolefin, at least one secondlayer arranged adjacent to said first layer and containing a liquidcrystalline polymer, and a tie layer that adheres the second layer tothe first layer, the second layer consisting essentially of a compoundedand compatibilized polymer blend formed by the liquid crystallinepolymer, a polyolefin and a compatibilizer, the liquid crystallinepolymer of the second layer forming a continuous phase, the second layerhaving an oxygen transmission rate of less than 150 cm³/(m²·d·bar),determined according to ASTM D 3985-81, and the laminate having a watervapor transmission rate of less than 10 g/(m²·24·h) at RH 80% 23° C.,determined according to ASTM F 1249-90, the second layer containing 60to 99% of the liquid crystalline polymer, 1 to 40% of the polyolefin,and 0.1 to 5% of the compatibilizer enhancing an interaction between theliquid crystalline polymer and the polyolefin, contents of the polymersand the compatibilizer being based upon total volume of the secondlayer.
 23. A laminate according to claim 22, wherein the substrate isone of paper board and paper.
 24. A laminate according to claim 22,wherein the substrate is formed as one of a cloth and a web.
 25. Alaminate according to claim 22, wherein, the polymer layer has one sideon which a cellulosic fiber layer is arranged and an opposite side onwhich a polyolefin layer is arranged.
 26. A method for manufacturing acontainer for food stuff or chemicals, which comprises the step offorming a container from a laminate comprising: a substrate; and atleast one polymer layer coated on a surface of said substrate to act asa barrier to transport of oxygen and water vapour through the laminate,the polymer layer consisting essentially of a multilayered polymerstructure having at least one first layer consisting of a polyolefin, atleast one second layer arranged adjacent to said first layer andcontaining a liquid crystalline polymer, and a tie layer that adheresthe second layer to the first layer, the second layer consistingessentially of a compounded and compatibilized polymer blend formed bythe liquid crystalline polymer, a polyolefin and a compatibilizer, theliquid crystalline polymer of the second layer forming a continuousphase, the second layer having an oxygen transmission rate of less than150 cm³/(m²·d·bar), determined according to ASTM D 3985-81, and thelaminate having a water vapor transmission rate of less than 10g/(m²·24·h) at RH 80% 23° C., determined according to ASTM F 1249-90,the second layer containing 60 to 99% of the liquid crystalline polymer,1 to 40% of the polyolefin, and 0.1 to 5% of the compatibilizerenhancing an interaction between the liquid crystalline polymer and thepolyolefin, contents of the polymers and the compatibilizer being basedupon total volume of the second layer.
 27. A multilayered polymer filmstructure for use as a barrier layer in packages, consisting essentiallyof: at least one first layer containing a polyolefin; at least onesecond layer arranged adjacent to said first layer and containing aliquid crystalline polymer, the second layer consisting essentially of acompounded and compatibilized polymer blend formed by the liquidcrystalline polymer, a polyolefin and a compatibilizer, the liquidcrystalline polymer of the second layer forming a continuous phase, thesecond layer having an oxygen transmission rate of less than 150cm³/(m²·d·bar), determined according to ASTM D 3985-81, and the integralfilm structure having a water vapour transmission rate of less than 10g/(m²·24·h) at RH 80% 23° C., determined according to ASTM F 1249-90,the second layer containing 60 to 99 parts by volume of the liquidcrystalline polymer, 1 to 40 parts by volume of the polyolefin, and upto 0.1 to 5 parts by volume of the compatibilizer enhancing aninteraction between the liquid crystalline polymer and the polyolefin,contents of the polymers and the compatibilizer being based upon totalvolume of the second layer; and a tie layer that adheres the secondlayer to the first layer, the compatibilizer being a functionalizedpolyolefin comprising an oleofinic polymer functionalized with one ofthe group consisting of epoxy, carboxylic acid, anhydride, hydroxyl,amine, carbonyl and oxazoline groups and combinations of these groups.28. A multilayered polymer film structure for use as a barrier layer inpackages, consisting essentially of: at least one first layer containinga polyolefin; at least one second layer arranged adjacent to said firstlayer and containing a liquid crystalline polymer, the second layerconsisting essentially of a compounded and compatibilized polymer blendformed by the liquid crystalline polymer, a polyolefin and acompatibilizer, the liquid crystalline polymer of the second layerforming a continuous phase, the second layer having an oxygentransmission rate of less than 150 cm³/(m²·d·bar), determined accordingto ASTM D 3985-81, and the integral film structure having a water vapourtransmission rate of less than 10 g/(m²·24·h) at RH 80% 23° C.,determined according to ASTM F 1249-90, the second layer containing 60to 99 parts by volume of the liquid crystalline polymer, 1 to 40 partsby volume of the polyolefin, and 0.1 to 5 parts by volume of thecompatibilizer enhancing an interaction between the liquid crystallinepolymer and the polyolefin, contents of the polymers and thecompatibilizer being based upon total volume of the second layer; and atie layer that adheres the second layer to the first layer, at least twoof the first layers being provided, one on each side of the secondlayer, the tie layer being of maleic anhydride grafted copolyethylene oneach side of the second layer for adhering each of the first layers to arespective side of the second layer.